Comment 1 for bug 2036761

ppa-purge is a pretty dangerous script to run due to the downgrade functionality that we should be discouraging use of.

It can create systems that look like they have supported components only but had everything messed up by downgrading from some PPA.

If the PPA added packages not available in other sources, removing them is fine. But if downgrades are involved it should come with reasonably strong warnings.

Generally speaking people should probably reinstall from scratch if they added a PPA that replaced important system packages.